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AC Coil - Induced Currents
AC Coil - Induced Currents
Principles Illustrated: Repulsion by induced magnetic fields
Location: Cabinet F, Shelf 4
A large electromagnet, with a movable iron core, is energized with AC power. An aluminum ring, placed over the extended core, is propelled upwards by about two feet when the coil is suddenly energized. The ring will also be levitated around the core if the power is left on.
WARNING: Rings left on the energized core will heat considerably!
AC Transformer
AC Transformer
Principles Illustrated: Magnetic Induction
Location: Cabinet F, Shelf 4
An AC powered coil makes the primary in a transformer. The secondary coil has an attached bulb. You can show that the power picked up in the secondary is affected by the distance between the coils.
LRC Circuit
LRC Circuit
Principles Illustrated: LRC Circuit
Location: Cabinet F, Shelf 4
An LRC circuit is driven with a signal generator. Light bulbs attached to the circuit help to visually demonstrate the frequency dependence of the current through the capacitor, the inductor, and the resistor.
Additionally, a separate demonstration displays the voltage across the resistor of an LRC on an oscilloscope. Upon sweeping the frequency, resonance is observed and may be displayed on over the document cam.
Magnet in Tube
Magnet in Tube
Principles Illustrated: Lenz' Law, Eddy Currents
Location: Cabinet F, Shelf 3
Two 'plugs' are dropped through a copper tube. One plug is made of aluminum and the other is a neodymium magnet. The aluminum plug drops through the tube in a 'normal' fashion, while the magnet plug takes a drastically longer time due to the force in response to the induced current in the tube wall.
Magnetic Damping-Swinging Plates
Magnetic Damping-Swinging Plates
Principles Illustrated: Eddy Currents
Location: Back Counter
Permanent magnets are mounted in an adjustable iron yoke to produce a strong field volume. Aluminum plates: 1 solid, 1 with rectangular openings, and 1 cut with multiple slots, are allowed to swing through the magnet gap.
Induced currents in the aluminum plates will cause strong motion damping in the solid plate, moderate damping in the plate with openings, and no damping in the slotted plate due to circular currents induced by the motion through the magnetic field.
Magnetic Induction
Magnetic Induction
Principles Illustrated: Magnetic Induction
Location: Back Counter
Three coils are attached to a galvanometer. Each coil has different number of turns. 200 800 3200 When a magnet is brought near each coil the galvanometer shows a deflection based on the amount of turns. The galvanometer is classroom size.
Motor and Generator
Motor and Generator
Principles Illustrated: Magnetic Induction
A versatile unit, switchable between DC motor and generator modes. In Motor mode, two neodymium magnets are used to generate a magnetic field, which causes the armature to rotate. While the motor is spinning, switch to Generator mode to create an induced current, lighting a small light bulb on the front of the unit.
Tesla Coil
Tesla Coil
Principles Illustrated: Magnetic Induction
Location: Cabinet F, Shelf 3
Powered by AC wall current, this table top tesla coil is a harmless source of high voltage, high frequency current. Attaching a large, clear, light bulb to the top of the coil demonstrates the workings of the popular 'plasma globe' toy.
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